Subsea oilfield communications system

ABSTRACT

A method for transmitting signals in a subsea environment includes determining that a quality of an acoustic signal is below a threshold. The acoustic signal travels from a first device, through water in the subsea environment, to a second device. A parameter of the first device, the second device, or both is then adjusted to improve the quality of the acoustic signal when the quality of the acoustic signal is below the threshold.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationNo. 62/530,883, filed on Jul. 11, 2017, the entirety of which is herebyincorporated by reference.

BACKGROUND

In offshore oil and gas operations, acoustic telemetry can providereal-time monitoring and remote control of vehicles and subsea assets.Such telemetry can, for example, provide communication with sensors,autonomous underwater vehicles (AUVs), remotely-operated vehicles(ROVs), untethered remotely-operated vehicles (UROVs), and others. Forsimplicity, “AUV” is used herein to refer to untethered vehicles withsome level of autonomy.

Acoustic telemetry is scalable: high bitrates can be obtained at shortdistances, and low bitrates can be obtained at long distances. However,subsea acoustic telemetry experiences signal absorption over the medium(e.g., water). This absorption becomes greater (i.e., worse) at higherfrequencies and longer ranges. Further, this type of telemetry issubjected to noise from equipment, such as vessels, rigs, subseafactories, and debris in the ocean. Acoustic signal propagation isgeometric, and therefore placement, directivity, and orientation of bothtransmitting and receiving elements can impact signal transmission.Further, the received signal can be subjected to platform dynamics. Forexample, the motion of the transmitting and receiving elements caninduce systematic signal distortion.

SUMMARY

This summary is provided to introduce a selection of concepts that arefurther described below in the detailed description. This summary is notintended to identify key or essential features of the claimed subjectmatter, nor is it intended to be used as an aid in limiting the scope ofthe claimed subject matter.

A method for transmitting signals in a subsea environment is disclosed.The method includes determining that a quality of an acoustic signal isbelow a threshold. The acoustic signal travels from a first device,through water in the subsea environment, to a second device. A parameterof the first device, the second device, or both is then adjusted toimprove the quality of the acoustic signal when the quality of theacoustic signal is below the threshold.

In another embodiment, the method includes transmitting a first signalfrom a first device to a first vehicle via a first short-hopcommunication link. The first device is positioned on or proximate to aseabed, and the first vehicle is configured to move in the subseaenvironment with respect to the first device. The method also includestransmitting a second signal from the first vehicle, through the subseaenvironment, to a second vehicle. The second vehicle is positioned at ashallower depth than the first vehicle, and the second signal is anacoustic signal. The method also includes transmitting a third signalfrom the second vehicle to a second device via a second short-hopcommunication link. The second device is positioned on a vessel or astructure that is positioned on or proximate to a sea surface, and thesecond vehicle is configured to move in the subsea environment withrespect to the second device. The first signal, the second signal, andthe third signal include common data. The method also includesdetermining that a quality of the second signal is below a threshold.The method also includes adjusting a parameter of the first vehicle, thesecond vehicle, or both to improve the quality of the second signal whenthe quality of the second signal is below the threshold.

A system for transmitting signals in a subsea environment is alsodisclosed. The system includes a seabed device positioned on orproximate to a seabed. The system also includes a first subsea vehicleconfigured to move in the subsea environment with respect to the seabeddevice. The first subsea vehicle is in communication with the seabeddevice (e.g., via a short-hop communication link). The system alsoincludes a second subsea vehicle positioned at a shallower depth thanthe first subsea vehicle. The first subsea vehicle is in communicationwith the second subsea vehicle via acoustic telemetry. The system alsoincludes a surface device positioned on a vessel or a structure that ispositioned on or proximate to a sea surface. The surface device is incommunication with the second subsea vehicle (e.g., via a short-hopcommunication link).

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate embodiments of the presentteachings and together with the description, serve to explain theprinciples of the present teachings. In the figures:

FIG. 1 illustrates a schematic view of a plurality of subseacommunication systems, according to an embodiment.

FIG. 2 illustrates a workflow diagram for using vehicle information tocorrect signal distortion, according to an embodiment.

FIG. 3 illustrates a schematic view of an operation of a subseacommunication system, according to an embodiment.

FIG. 4 illustrates a flowchart of a method for communicating in a subseaenvironment, according to an embodiment.

DETAILED DESCRIPTION

Reference will now be made in detail to specific embodiments illustratedin the accompanying drawings and figures. In the following detaileddescription, numerous specific details are set forth in order to providea thorough understanding of the invention. However, it will be apparentto one of ordinary skill in the art that embodiments may be practicedwithout these specific details. In other instances, well-known methods,procedures, components, circuits, and networks have not been describedin detail so as not to unnecessarily obscure aspects of the embodiments.

It will also be understood that, although the terms first, second, etc.may be used herein to describe various elements, these elements shouldnot be limited by these terms. These terms are only used to distinguishone element from another. For example, a first object could be termed asecond object, and, similarly, a second object could be termed a firstobject, without departing from the scope of the present disclosure.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting. As used in thedescription and the appended claims, the singular forms “a,” “an” and“the” are intended to include the plural forms as well, unless thecontext clearly indicates otherwise. It will also be understood that theterm “and/or” as used herein refers to and encompasses any and possiblecombinations of one or more of the associated listed items. It will befurther understood that the terms “includes,” “including,” “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, operations, elements, components,and/or groups thereof. Further, as used herein, the term “if” may beconstrued to mean “when” or “upon” or “in response to determining” or“in response to detecting,” depending on the context.

Sensors and Stations Network

FIG. 1 illustrates a schematic view of a plurality of subsurfacecommunication systems 100, according to an embodiment. The systems 100are generally partitioned, at least conceptually, in terms of depthbelow the water's surface. For example, as shown, the systems 100 may bepartitioned into the following regions: surface 102, shallow 104,intermediate 106, deepwater 108, and seabed 110. The precisedelineations between these regions (apart from surface 102, which is notunder the water) may be chosen at any suitable depth according to avariety of implementation-specific factors which are beyond the scope ofthe present disclosure, with the general idea that relative depthsmatter more than absolute depth classifications. In general, a device inthe deepwater 108 and/or seabed 110 can be a vehicle or equipment thatis a far distance away from a surface system, with which it is tocommunicate. Thus, one or more intermediary devices in one or more ofthe regions 104, 106, 108 between the seabed 110 and the surface 102 maybe called upon to enhance communications.

Several potential devices that may occupy the various regions are alsoillustrated. For example, a “short-hop” communication link 120 may beestablished between seabed hardware 122 and a vehicle 124, such as anAUV, positioned in the deepwater region 108. The AUV 124 may include amodem, which may be configured to communicate with one or more other(e.g., shallower) modems, as will be described in greater detail below.The short-hop communication link 120 may be wired or may be wireless(e.g., high bitrate). Moreover, the short-hop communication link 120between surface/shallow and deepwater/seabed vessels can be any type of(e.g., restricted range) connection including acoustics, cable link,optical link, electromagnetic link, and radiofrequency link. In someembodiments, the short-hop communication link 120 can be provided by arigid and/or articulating linkage, a cable, a flexible member, or thelike. In some embodiments, the AUV 124 may include a towable body thatis tethered to the AUV 124, with transducers/sensors positioned on thetowable body.

Reference number 130 represents a short-hop communication link betweenseabed hardware 132 and another vehicle (e.g., an autonomous vehicle)134, which may include a modem and/or a transducer. Reference number 140represents seabed hardware 142 with a modem, which has established acommunication link with another device. The seabed hardware 142 may alsoact as a relay station to receive and repeat communications.

Reference number 150 illustrates an intermediate-depth (e.g.,autonomous) vehicle. The intermediate-depth vehicle 150 may include amodem with the ability to receive and transmit signals. In particular,the modem of the intermediate-depth vehicle 150 may have the ability toact as a repeater, relaying signals between two, far-apart devices. Insome embodiments, the intermediate-depth vehicle 150 (e.g., an AUV) mayact as a relay station, with smart transducers/sensors to sectorize,and/or bafflers to separate, upward and/or downward channels. In someembodiments, the AUV 150 may be connected to a towable body that mayinclude the transducers/sensors, which may be connected via a short-hop(e.g., tethered to) the AUV 150.

Reference number 160 represents a short-hop link between a stationarysurface structure (e.g., an oil platform) 162 and a subsea vehicle(e.g., ROV) 164 that is positioned in the shallow region 104 andincludes a modem. The subsea vehicle 164 may be tethered to the surfacestructure 162 or may be wireless. The subsea vehicle 164 may be an ROVand may carry a subsea model, active acoustic elements, or both.

Reference number 170 illustrates a short-hop link between a mobilesurface vessel (e.g., a ship, Wave Glider, etc.) 172 and ashallow-water, submersible vehicle 174, such as a towed device, ROV,AUV, etc. The surface vessel 172 can be a maneuverable vessel, a vesselwith restricted maneuverability (e.g., a platform supply vessel (PSV)),or a vessel with no maneuverability (e.g., a floating production storageand offloading (FPSO)). Modem or transducer/sensor elements of the modemmay be separated from the surface vessel 172 and (e.g., placed withinshallow devices/vehicles), which may provide versatile positioning, incomparison to placing the modem/transducer elements on the surfacevessel. In addition, an energy payload used to operate the submersiblevehicle 174 (e.g. batteries) generally can be shared between surface andshallow vessels efficiently. Thus, there is gain to moving the modemcomponents to the shallow-water devices, with little cost.

Reference number 180 illustrates a surface link between the stationarysurface structure 162 and the surface vessel 172, which may be wirelesssuch as a radiofrequency, optical, cable, etc., acting as a gateway to arig or platform.

Example Applications for the System

Localization: At the surface, a structure 162 or vessel 172 may haveaccess to a GPS signal and may therefore have a knowable, preciselocation on the Earth's surface. GPS coordinates can be transmitted atregular intervals to the shallow vessel 164, 174 using the short-hoplink 160, 170. The relative distance between the shallow vessel 164, 174and the surface structure or vessel 162, 172 can be estimated using thefusion of multiple sensors including an inertial navigation unit(including a set of gyroscopes and accelerometers), pressure depthsensors, and/or estimated direction of arrival from an array of acousticsensors.

Placement for active noise avoidance and channel optimization: In someunderwater communication environments, sources and receivers have afixed position, and the receiver is used to correct the distortions ofthe propagation channel and alleviate the adverse effects of the noiseon signal reliability. In the context of the network illustrated in FIG.1, an additional degree of freedom is available as the positioning ofthe shallow vessel(s) 164, 174 and/or the deepwater vessels 124, 134 canbe adjusted independently. As a result, the telemetry uplink anddownlink can be enhanced following one or more of several differentstrategies.

For example, before communication is established, both shallow vessels164, 174 and/or deepwater vessels 124, 134 can scan the environment (inthis case a half-sphere horizon) to detect the presence of acousticinterferences (i.e., hot spots) at a given solid angle. If hot spots areidentified, corresponding solid angles may be marked as unsuitable, asit may be considered likely to be problematic for communication. Infollowing point-to-point communication, the position of the vessels 124,134, 164, 174 may be adaptively adjusted such that the interferenceswith line of sight is minimized or at least reduced.

In another example, before the communication is established, anagreed-upon sequence of acoustic waveforms may be exchanged between themodems of the shallow vessels 164, 174 and/or deepwater vessels 124,134. This allows both modems to assess the quality of the communicationchannel. If the channel is deemed to be unsuitable (e.g., due to a highsignal-to-noise ratio), the position of the vessels 124, 134, 164, 174may be adjusted until a proper channel is found. Within each cycle,additional parameters such as source and receiver focalization can alsobe modified so the effect of the propagation channel can be evaluated.Once a satisfactory configuration is identified, shallow vessels 164,174 and/or deepwater vessels 124, 134 are locked in position and thecommunication may begin.

Uplink/downlink repeater: In underwater environments, and especially forwideband communication, attenuation in the underwater medium can besevere, such that the effective communication range is short. Further,even when signal attenuation is not severe, as the spatial coverage ofthe beam solid angle increases with distance, long-distancetransmissions are likely to generate multiple reflections at theair-water and water-seabed interfaces. In such a case, the transmissionpower may be reduced, but generally at the cost of reducing theeffective range, to reduce the interference caused by multipathpropagation. In such case, an additional underwater vessel 150 at anintermediate level/depth can be employed as a repeater. This vessel 150may receive the acoustic uplink signal and retransmit it (with eventualmodifications) to the uplink. The downlink may proceed similarly, but inthe opposite direction.

Further, even when attenuation is severe, a combination of bafflingmaterial, directional transducers, and signal design can be employed toenhance communication between two nodes via an intermediate device. Asan example, signal design can be used to separate the channel throughtime-sharing, frequency-sharing, code-sharing, and/or sub-carriersharing. Further, multi-user detection and network coding techniques canbe used in this networked system such that efficient channel-sharing ispossible. The position of the repeater, and the communication parametersused in the upper and lower links, can be jointly adjusted to enhancesignal transmission depending on the situation.

Further, the two links may rely on different forms of communication. Forexample, when operating near a surface vessel 172 or equipment (e.g., ona structure 162) that is very noisy, an optical link may connect fromthe surface vessel 172 or the structure 162 onto a repeater displacedaway from the noise source that then uses acoustic telemetry tocommunicate to the modem on the vehicle near the seabed. Similarly, inthe seabed hardware 122, 132, 142, a modem or transducer/sensor elementsmay be placed away from noisy seabed equipment to mitigate the effect ofnoise, and connected to the equipment through various short-hop options.

Wireless multi-hop or relay network: The system 100 may facilitateunderwater inspection and maintenance over very long distances (up to100 km). For example, the autonomous vehicle 124, 134, 164, 174 may beable to travel at high speed (potentially faster than the surface vessel172), and the surface vessel 172 may manage multiple autonomous vehicles124, 134, 164, 174 that cover distinct underwater areas. Thus, thesurface vessel 172 may be far off from the autonomous vehicle(s) 124,134, 164, 174. The acoustic conditions from the autonomous vehicle(s)124, 134, 164, 174 to the surface vessel 172 may be insufficient toprovide a one-hop communication link. Further, tangential acousticpropagation can be challenging due to a “shadowing” effect. Accordingly,a network of communication nodes may be deployed to provide a multi-hopnetwork. An example of such a configuration includes having a fixedseabed node, in which the transducer orientation may be adapted tocommunicate with an autonomous vehicle 124, 134 roaming within or instationary positioned in one area. The seabed node 126 can also maintainthe link with the surface vessel 172. Another configuration may use anautonomous vehicle 150 as a relay station. The parameters of the nodessuch as location, transducer orientation, and physical layer parameterscan be adapted depending on the acoustic conditions.

Multiple transducers/sensors array: Arrays of multipletransducers/sensors may be employed for enhancing bandwidth usage. Anexample is to adjust Q factors of the transducers and use multipletransducers in one modem to increase the available bandwidth. Further,transducers with several beam-forming angles may be employed, allowingthe transducers to iteratively adjust the energy at the receiver node.

Synthetic aperture communication: In this configuration, two or moresurface nodes (e.g., on the surface structure 162 and/or the surfacevessel 172) listen for underwater communication. Precise timing onrecorded samples using GPS clocks and measurement samples are exchangedvia the surface link 180. One of the surface nodes may collect thesamples from the configurations and decode the communication signal.This configuration may leverage spatial diversity to compensate forchannel distortion and noise. The use of multiple transducers, sensorarrays, and synthetic aperture communication can be combined with smartplacements, as described above.

Smart Signal Processing for Reliable Communication

Underwater acoustics can present challenges for several reasons. Forexample, vehicle motion (e.g., both transmitter and receiver) andchanges in the channel (e.g., due to sea state variations, waves,movement of reflectors, etc.) can impact communication. This may becompensated for using “smart” signal processing. Further, noise from thevehicle or equipment that the modem or acoustic components are mountedon can be present. Additionally, a drop in signal quality and data rateas distance between the transmitter and receiver is increased, or isaffected by noise, may also be experienced.

Platform and vehicle dynamics, and derivative, communication signaldistortion parameters, may be distinguished using, for example,effective Doppler, frequency shifts, and/or time shifts. The latter canbe derived from the former, but, in some embodiments, the former may notbe derived from the latter. Accordingly, embodiments of the presentdisclosure may use vehicle state data to correct the transmitted and/orreceived signal. For example, if an estimate of vehicle motion iscalculated, acceleration data can be derived and used to correct thetelemetry signal, as shown in FIG. 2, which is discussed in greaterdetail below.

In one embodiment, a receiving modem can estimate an effective signaldistortion parameter, and associate this parameter with a sender ID, totrack its change over time. In another embodiment, a transmitting modemcan compute effective signal distortion due to its own motion, and thenapply pre-distortion or pre-compensation of its own signal such that itis easier to decode by a receiver, even if that receiver does not knowthe state of the transmitting modem's vehicle. In yet anotherembodiment, a transmitting modem can obtain vehicle motion data from itsonboard sensor(s), and send this information to the receiving modems.Each receiving modem can then use this information, in addition to itsown vehicle motion information, to derive the effective signaldistortion parameter, which can then be used to make corrections.

There are several ways to send the relevant information. One way is toembed the information into the data packet. Another is to send theinformation over a more reliable link, for example, using a low-bitratelink. If vehicle or equipment noise is an impediment, the position,velocity, acceleration, etc., of the vehicle or the equipment can beadjusted to enable a higher signal-to-noise ratio. For example, thevehicle can be stopped or slowed, and the operation of pumps orcompressors slowed or stopped. When a prediction or estimate of channelconditions based on modem positions and configurations are available,such information can be used. This way of adjusting vehicle position andvelocity in order to enhance signal quality may be particularly usefulwhen this vehicle is conveying either sensors and/or transducers, oracting as a relay station.

In some embodiments, machine learning can be used to increase signaltransmission quality. For example, machine learning can be used to learnabout environment and noise. Further, classification and identificationof obstacles or noise sources can be achieved. Acoustics can be used tolearn about the underwater environment. A framework for enhancing signalreception may be based on conditions, with a handshaking protocol toadapt spatial apertures based on received signal quality. Sensor datacan also be applied to learn about noise from specific structures.

FIG. 2 illustrates a workflow diagram 200 of a signal transmissionsystem 100, according to an embodiment. As shown, the system 100 mayinclude a transmitting modem 210, which may be or be a part of a firstdevice, and a receiving modem 220, which may be or be a part of a seconddevice. The first and second devices may also each include or be coupledto one or more motion sensors 212, 222 and a vehicle controller 214,224. The receiving modem 220 may also be coupled to a controller 230configured to compute effective signal distortion. The receiving modem220 may pass along information on the receiving vehicle (second device)and information regarding the transmitting vehicle (first device). Suchinformation may include the position of the respective devices,transmission angles, etc. The controller 230 may calculate signaldistortion information or correct and pass such information back to thereceiving modem 220. In turn, the second device may adjust its position,or signal the first device to adjust its position, or may change theoperation of equipment, to reduce the signal distortion, if thedistortion is above a certain level.

FIG. 3 illustrates a schematic view of an operation of a subseacommunication system 300, according to an embodiment. On the left side,a link is established between a surface structure 310 and a seafloordevice 320 via an intermediate-depth vehicle 330 (acting as a signalrepeater). On the right side, a link is established between a surfacevehicle 340, towing, wired to, or otherwise in short-hope communicationwith a shallow vessel 350 that includes a modem. It will be appreciatedthat these links can be combined, e.g., such that the intermediate depthvehicle 330 acts as a repeater to send/receive communication to/from ashallow vessel (or a deepwater vessel in short-hop communication withseabed devices).

FIG. 4 illustrates a flowchart of a method 400 for communicating in asubsea environment, according to an embodiment. The method 400 mayinclude transmitting a first signal from a first device to a firstvehicle via a first short-hop communication link, as at 402. In at leastone embodiment, the first device (e.g., hardware 122, 132, 142) ispositioned on or proximate to the seabed 110, and the first vehicle 124,134 is configured to move with respect to the first device. In anotherembodiment, the first device may be positioned on the structure 162 orthe vessel 172, and the first vehicle 164, 174 is configured to movewith respect to the first device.

The method 400 may also include transmitting a second signal from thefirst vehicle, through the subsea environment, to a second vehicle, asat 404. The second vehicle may be positioned at a different depth thanthe first vehicle. The second signal may be or include an acousticsignal.

The method 400 may also include transmitting a third signal from thesecond vehicle to a second device via a second short-hop communicationlink, as at 406. In at least one embodiment, the second device may bepositioned on the structure 162 or the vessel 172, and the secondvehicle 164, 174 is configured to move with respect to the seconddevice. In another embodiment, the second device (e.g., hardware 122,132, 142) is positioned on or proximate to the seabed 110, and thesecond vehicle 124, 134 is configured to move with respect to the seconddevice. The first signal, the second signal, and the third signal mayinclude at least some common data.

The method 400 may also include determining that a quality of the secondsignal is below a threshold, as at 408. In at least one embodiment,determining that the quality of the second signal is below the thresholdmay include the first vehicle and/or the second vehicle scanning thesubsea environment between the first and second vehicles to detect thepresence of acoustic interferences at a given solid angle. For example,the scanning may be or include a half-sphere horizon.

The method 400 may also include adjusting a parameter of the firstvehicle, the second vehicle, or both to improve the quality of thesecond signal when the quality of the second signal is below thethreshold, as at 410. Adjusting the parameter may cause the quality ofthe second signal to rise above the threshold. The parameter may be orinclude a position, velocity, and/or acceleration of the first vehicle(e.g., the vehicle 124, 134). The parameter may also or instead be orinclude a position, velocity, and/or acceleration of the second vehicle(e.g., the vehicle 164, 174). Adjusting the position, velocity, and/oracceleration of the first vehicle and/or the second vehicle may adjustthe path of the second signal (e.g., to avoid acoustic interferences).

The parameter may also or instead be or include a strength of the secondsignal, a frequency or the second signal, a wavelength of the secondsignal, or a combination thereof. For example, the strength, frequency,and/or wavelength may be increased or decreased to improve the qualityof the signal.

The parameter may also or instead be or include operation of equipment(e.g., pumps, compressors, motors, etc.). For example, equipment on orproximate to the seabed hardware 122, 132, 142, the vehicle(s) 124, 134,164, 174, the structure 162, and/or the vessel 172 may be slowed or shutdown to reduce acoustic interference.

The method 400 may also include repeating the second signal with a thirdvehicle that is positioned at a depth between the first vehicle and thesecond vehicle, as at 412. The third vehicle may be positioned in thewater of the subsea environment. For example, the third vehicle may beor include the vehicle 150. Repeating the second signal may cause thestrength (i.e., amplitude) of the second signal received by the secondvehicle to be greater than if no repeater is used. In addition,transmitting the second signal from the first vehicle to the thirdvehicle to the second vehicle, or from the second vehicle to the thirdvehicle to the first vehicle, may enable the second signal to bypass anacoustic interference positioned in the line of sight between the firstand second vehicles (e.g., when the third vehicle is not positionedalong the line).

As used herein, the terms “inner” and “outer”; “up” and “down”; “upper”and “lower”; “upward” and “downward”; “above” and “below”; “inward” and“outward”; and other like terms as used herein refer to relativepositions to one another and are not intended to denote a particulardirection or spatial orientation. The terms “couple,” “coupled,”“connect,” “connection,” “connected,” “in connection with,” and“connecting” refer to “in direct connection with” or “in connection withvia one or more intermediate elements or members.”

The foregoing description, for purpose of explanation, has beendescribed with reference to specific embodiments. However, theillustrative discussions above are not intended to be exhaustive or tolimit the invention to the precise forms disclosed. Many modificationsand variations are possible in view of the above teachings. Moreover,the order in which the elements of the methods described herein areillustrate and described may be re-arranged, and/or two or more elementsmay occur simultaneously. The embodiments were chosen and described inorder to best explain the principals of the invention and its practicalapplications, to thereby enable others skilled in the art to bestutilize the invention and various embodiments with various modificationsas are suited to the particular use contemplated.

What is claimed is:
 1. A method for transmitting signals in a subseaenvironment, comprising: determining that a quality of an acousticsignal is below a threshold, wherein the acoustic signal travels from afirst device, through water in the subsea environment, to a seconddevice; and adjusting a parameter of the first device, the seconddevice, or both to improve the quality of the acoustic signal when thequality of the acoustic signal is below the threshold whereindetermining that the quality of the acoustic signal is below thethreshold comprises scanning the subsea environment to detect anacoustic interference in a transmission path between the first deviceand the second device.
 2. The method of claim 1, wherein scanning thesubsea environment comprises scanning a half-sphere horizon between thefirst device and the second device.
 3. The method of claim 1, whereinadjusting the parameter of the first device, the second device, or bothcomprises adjusting a position of the first device, the second device,or both.
 4. The method of claim 1, wherein adjusting the parameter ofthe first device, the second device, or both comprises adjusting avelocity or an acceleration of the first device, the second device, orboth.
 5. The method of claim 1, wherein adjusting the parameter of thefirst device, the second device, or both comprises adjusting slowing orshutting down noise-making equipment on or proximate to first device,the second device, or both.
 6. The method of claim 1, wherein adjustingthe parameter of the first device, the second device, or both comprisesadjusting a strength of the acoustic signal.
 7. The method of claim 6,wherein adjusting the strength of the acoustic signal comprises reducingthe strength of the acoustic signal and further comprising repeating theacoustic signal at a third device that is positioned at a depth betweenthe first device and the second device in the water in the subseaenvironment.
 8. The method of claim 1, further comprising repeating theacoustic signal at a third device that is positioned at a depth betweenthe first device and the second device in the water in the subseaenvironment, wherein repeating the acoustic signal at the third deviceenables the acoustic signal to bypass an acoustic interference that ispositioned between the first device and the second device.
 9. A methodfor transmitting signals in a subsea environment, comprising:transmitting a first signal from a first device to a first vehicle via afirst short-hop communication link, wherein the first device ispositioned on or proximate to a seabed, and wherein the first vehicle isconfigured to move in the subsea environment with respect to the firstdevice; transmitting a second signal from the first vehicle, through thesubsea environment, to a second vehicle, wherein the second vehicle ispositioned at a shallower depth than the first vehicle, and wherein thesecond signal is an acoustic signal; transmitting a third signal fromthe second vehicle to a second device via a second short-hopcommunication link, wherein the second device is positioned on a vesselor a structure that is positioned on or proximate to a sea surface,wherein the second vehicle is configured to move in the subseaenvironment with respect to the second device, and wherein the firstsignal, the second signal, and the third signal comprise common data;determining that a quality of the second signal is below a threshold;and adjusting a parameter of the first vehicle, the second vehicle, orboth to improve the quality of the second signal when the quality of thesecond signal is below the threshold.
 10. The method of claim 9, whereindetermining that the quality of the second signal is below the thresholdcomprises: testing the quality of the second signal along a plurality ofsolid angles between the first vehicle and the second vehicle; anddetermining hot spots in the subsea environment based on whereinterference is recorded during the testing.
 11. The method of claim 9,wherein determining that the quality of the second signal is below thethreshold comprises determining that a line of sight between the firstdevice and the second device includes a hot spot for signalinterference, and wherein adjusting the parameter comprises adjustingthe line of sight to avoid the hot spot.
 12. The method of claim 11,wherein adjusting the line of sight comprises moving the first vehicle,the second vehicle, or both.
 13. The method of claim 11, whereinadjusting the line of sight comprises repeating the second signal at athird vehicle that is positioned at a depth between the first vehicleand the second vehicle, and wherein the third vehicle is not in the lineof sight.
 14. A system for transmitting signals in a subsea environment,comprising: a seabed device positioned on or proximate to a seabed; afirst subsea vehicle configured to move in the subsea environment withrespect to the seabed device, wherein the first subsea vehicle is incommunication with the seabed device; a second subsea vehicle positionedat a shallower depth than the first subsea vehicle, wherein the firstsubsea vehicle is in communication with the second subsea vehicle viaacoustic telemetry; and a surface device positioned on a vessel or astructure that is positioned on or proximate to a sea surface, whereinthe surface device is in communication with the second subsea vehicle;wherein the surface device and the second subsea vehicle share a modem,a transducer element, a sensor element, or a combination thereof. 15.The system of claim 14, wherein a first portion of the modem, thetransducer element, the sensor element, or the combination thereof ispositioned on the surface device, wherein a second portion of the modem,the transducer element, the sensor element, or the combination thereofis positioned on the second subsea vehicle, and wherein the secondportion comprises an acoustic active element.
 16. The system of claim14, wherein the second subsea vehicle is autonomous and configured tochange position to increase a quality of the acoustic telemetry inresponse to the quality of the acoustic telemetry being determined to bebelow a threshold.
 17. The system of claim 14, wherein the first subseavehicle is tethered to the seabed device, and wherein the second subseavehicle is tethered to the surface device.
 18. The system of claim 14,further comprising a third subsea vehicle positioned at a depth betweenthe first subsea vehicle and the second subsea vehicle, wherein thethird subsea vehicle is configured to move with respect to the firstsubsea vehicle and the second subsea vehicle and to act as a repeaterfor the acoustic telemetry to improve a quality of the acoustictelemetry.